At a middle school, 21% of all students play football, and 13% of all students play basketball. 25% of all students play football or basketball. What is the probability that a student plays both sports?
+128408 Let's suppose that there are 100 students at the school
Then
21 play football
13 play basketball
25 play either
N ( play either) = N(play football) + N (play basketball) - N (who play both )
25 = 21 + 13 - N (who play both)
25 - 21 -13 = - N (who play both)
-9 = - N (who play both )
9 = N ( who play both )
